排序方式: 共有21条查询结果,搜索用时 31 毫秒
1.
Timothy Buttsworth 《Mathematische Nachrichten》2019,292(4):747-759
Let G be a three‐dimensional unimodular Lie group, and let T be a left‐invariant symmetric (0,2)‐tensor field on G. We provide the necessary and sufficient conditions on T for the existence of a pair consisting of a left‐invariant Riemannian metric g and a positive constant c such that , where is the Ricci curvature of g. We also discuss the uniqueness of such pairs and show that, in most cases, there exists at most one positive constant c such that is solvable for some left‐invariant Riemannian metric g. 相似文献
2.
Trent D Lund Timothy W West Lilyan Y Tian Lihong H Bu Daniel L Simmons Kenneth DR Setchell Herman Adlercreutz Edwin D Lephart 《BMC neuroscience》2001,2(1):20-13
Background
In learning and memory tasks, requiring visual spatial memory (VSM), males exhibit superior performance to females (a difference attributed to the hormonal influence of estrogen). This study examined the influence of phytoestrogens (estrogen-like plant compounds) on VSM, utilizing radial arm-maze methods to examine varying aspects of memory. Additionally, brain phytoestrogen, calbindin (CALB), and cyclooxygenase-2 (COX-2) levels were determined. 相似文献3.
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Timothy Buttsworth 《Annals of Global Analysis and Geometry》2018,54(1):155-171
Let \(G{/}H\) be a compact homogeneous space, and let \(\hat{g}_0\) and \(\hat{g}_1\) be G-invariant Riemannian metrics on \(G/H\). We consider the problem of finding a G-invariant Einstein metric g on the manifold \(G/H\times [0,1]\) subject to the constraint that g restricted to \(G{/}H\times \{0\}\) and \(G/H\times \{1\}\) coincides with \(\hat{g}_0\) and \(\hat{g}_1\), respectively. By assuming that the isotropy representation of \(G/H\) consists of pairwise inequivalent irreducible summands, we show that we can always find such an Einstein metric. 相似文献
7.
Glued-diaphragm fibre optic pressure sensors that utilize standard telecommunications components which are based on Fabry–Perot
interferometry are appealing in a number of respects. Principally, they have high spatial and temporal resolution and are
low in cost. These features potentially make them well suited to operation in extreme environments produced in short-duration
high-enthalpy wind tunnel facilities where spatial and temporal resolution are essential, but attrition rates for sensors
are typically very high. The sensors we consider utilize a zirconia ferrule substrate and a thin copper foil which are bonded
together using an adhesive. The sensors show a fast response and can measure fluctuations with a frequency up to 250 kHz.
The sensors also have a high spatial resolution on the order of 0.1 mm. However, with the interrogation and calibration processes
adopted in this work, apparent errors of up to 30% of the maximum pressure have been observed. Such errors are primarily caused
by mechanical hysteresis and adhesive viscoelasticity. If a dynamic calibration is adopted, the maximum measurement error
can be limited to about 10% of the maximum pressure. However, a better approach is to eliminate the adhesive from the construction
process or design the diaphragm and substrate in a way that does not require the adhesive to carry a significant fraction
of the mechanical loading.
相似文献
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DR.G. Domairry A. Mohsenzadeh M. Famouri 《Communications in Nonlinear Science & Numerical Simulation》2009,14(1):85-95
In this paper Jeffery–Hamel flow has been studied and its nonlinear ordinary differential equation has been solved through homotopy analysis method (HAM). The obtained solution in comparison with the numerical ones represents a remarkable accuracy. The results also indicate that HAM can provide us with a convenient way to control and adjust the convergence region. 相似文献
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Crystal Blake Kimberly M Fabick Kenneth DR Setchell Trent D Lund Edwin D Lephart 《BMC neuroscience》2011,12(1):28
Background
Soy-derived isoflavones potentially protect against obesity and depression. In five different studies we examined the influence of soy-containing diets or equol injections on depression, serotonin levels, body weight gain (BW) and white adipose tissue (WAT) deposition in female Long-Evans rats at various stages of life [rats were intact, ovariectomized or experienced natural ovarian failure (NOF)]. 相似文献10.
R.N. Buttsworth 《Journal of Number Theory》1980,12(4):487-498
The polynomial functions f1, f2,…, fm are found to have highest common factor h for a set of values of the variables x1, x2,…,xm whose asymptotic density is For the special case f1(x) = f2(x) = … = fm(x) = x and h = 1 the above formula reduces to , the density if m-tuples with highest common factor 1. Necessary and sufficient conditions on the polynomials f1, f2,…, fm for the asymptotic density to be zero are found. In particular it is shown that either the polynomials may never have highest common factor h or else h is the highest common factor infinitely often and in fact with positive density. 相似文献